Thin film solar cell and preparation method thereof

Abstract

The invention provides a thin film solar cell and a preparation method thereof. The thin-film solar cell comprises a glass substrate, wherein a front electrode layer, a window layer, a light absorption layer and a back electrode layer are sequentially laminated on the glass substrate; the thin-film solar cell is provided with a plurality of grooves, and the grooves penetrate through the back electrode layer and partially cut off the light absorption layer; the ratio of the cutting depth of the light absorption layer to the total thickness of the light absorption layer is (0.2-0.8): 1. Through penetrating through the back electrode layer and the cut-off part of the light absorption layer, local short connection of the thin film solar cell caused by contact between residual particles generated during scribing and the front and rear electrode layers can be effectively prevented, and short connection caused by contact between metal and the front and rear electrode layers due to a groove edge curling phenomenon during lamination packaging can be avoided; and the short circuit problem of the thin-film solar cell is avoided. According to the method, the process difficulty is effectively reduced, the process window is expanded, and the error-tolerant rate is increased. Therefore, the design of the invention greatly weakens the influence of residual particles and groove hemming phenomena generated during scribing on the conversion efficiency of the thin-film solar cell. Therefore, the design greatly weakens the influence of the scribing of the groove on the conversion efficiency of the thin film solar cell.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a thin-film solar cell and a preparation method thereof. Background Art

[0002] As global attention to environmental protection continues to grow, the environmental advantages of thin-film solar cells, a representative source of clean and renewable energy, are becoming increasingly prominent. Thin-film solar cells produce no pollutants during use, meeting the requirements of sustainable development. Cadmium telluride thin-film solar technology, with its high efficiency, low cost, and environmentally friendly characteristics, holds a key position in the solar energy field.

[0003] In the preparation of thin-film solar cells, laser scribing can be used to divide the cell into individual sub-cells. However, tiny dust is generated during the scribing process. The dust removal device will absorb some of it, and some will remain in the gaps of the scribing and cannot be removed. These residual particles will cause local short circuits in the thin-film solar cell, affecting the cell conversion efficiency.

[0004] To this end, researchers have studied the problem of local short circuits in thin-film solar cells caused by metal particles remaining in the laser-scribed grooves after laser scribing, which leads to a decrease in solar cell efficiency, and have also studied technical issues that affect solar cell efficiency. For example, patent CN106229377A discloses a method for preventing short circuits in thin-film solar cells after edge scanning, comprising the following steps: (A) providing a substrate; (B) depositing a transparent conductive oxide film used as a front electrode of a thin-film solar cell on the substrate; (C) depositing a thin-film solar cell on the surface of the transparent conductive oxide film; (D) depositing a layer of metal back electrode on the thin-film solar cell; (E) performing P3 laser scribing on the thin-film solar cell to divide it into tiny sub-cell units; (F) generating a non-conductive or low-conductive thin film on the surface of the thin-film solar cell after the P3 laser scribing process; and (G) performing edge scanning on the thin-film solar cell after the thin film is generated in the previous step. This existing technology can effectively prevent the tiny metal back electrode particles formed after edge scanning from filling the laser-scribed grooves, thereby preventing local short circuits in the thin-film solar cell and affecting the efficiency of the solar cell. However, this patent has limitations. P3 scribing not only produces tiny metal back electrode particles, but also causes curling. This curling can lead to conduction between the metal and FTO after lamination and packaging, causing a short circuit in the solar cell and affecting conversion efficiency. Furthermore, by adding a non-conductive or low-conductivity film layer after the P3 scribing, changes in the thickness and uniformity of the film layer can affect the conversion efficiency of thin-film solar cells. Furthermore, the addition of the film layer can increase the overall cost of thin-film solar cells.

[0005] Therefore, how to effectively prevent laser scribing from causing local short circuits in thin-film solar cells and prevent the thin-film solar energy conversion efficiency from being affected is a technical problem that needs to be solved urgently. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide a thin-film solar cell and a method for manufacturing the same. This invention utilizes laser scribing to penetrate the back electrode layer and partially scribe the light-absorbing layer. This not only reduces process difficulty, expands the process window, and increases fault tolerance, but also effectively prevents residual particles from the scribing from contacting the front electrode layer and causing local short circuits in the thin-film solar cell. Furthermore, the curling of the grooves after lamination and packaging does not cause contact and conduction between the metal and the front electrode layer, thus avoiding the problem of local short circuits in the thin-film solar cell. Therefore, this design significantly reduces the impact of the groove scribing on the conversion efficiency of the thin-film solar cell.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a thin-film solar cell, comprising a glass substrate on which a front electrode layer, a window layer, a light absorption layer, and a back electrode layer are sequentially stacked.

[0009] The thin-film solar cell has a plurality of grooves, which penetrate the back electrode layer and partially cut through the light absorption layer; the ratio of the cutting depth of the light absorption layer to the total thickness of the light absorption layer is (0.2-0.8):1.

[0010] The present invention uses laser scribing to penetrate the back electrode layer and partially sever the light absorption layer. This not only reduces process difficulty, expands the process window, and increases fault tolerance, but also effectively prevents residual particles from the scribing from contacting the front electrode layer and causing local short circuits in the thin-film solar cell. Furthermore, the curling of the grooves after lamination and packaging does not cause contact and conduction between the metal and the front electrode layer, thus avoiding the problem of local short circuits in the thin-film solar cell. Therefore, this design significantly reduces the impact of the groove scribing on the conversion efficiency of the thin-film solar cell.

[0011] It should be noted that several refers to at least one, for example, it can be 1, 2, 3 or 4, etc.

[0012] In the present invention, the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):1, for example, it can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1 or 0.8:1.

[0013] In the present invention, the appropriate ratio of the scratch depth of the light absorption layer to the total thickness of the light absorption layer helps to prevent the occurrence of local short circuits and improve the performance and stability of the battery; secondly, it is conducive to improving the battery's absorption and utilization efficiency of light, thereby improving the battery's photoelectric conversion efficiency; and, it helps to enhance the stability of the battery structure, especially has a certain inhibitory effect on problems such as curling and warping that are prone to occur in the battery.

[0014] Preferably, the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.4-0.6):1.

[0015] Preferably, the material of the front electrode layer includes any one of FTO (fluorine-doped tin dioxide), ITO (indium tin oxide) or BZO (boron-doped zinc oxide), or a combination of at least two of them.

[0016] Preferably, the material of the window layer includes any one of CdS, CdSe or CdSeTe, or a combination of at least two of them.

[0017] Preferably, the material of the light absorbing layer includes CdTe.

[0018] Preferably, the material of the back electrode layer includes any one of Mo, Cr or Al, or a combination of at least two of them.

[0019] Preferably, the thickness of the front electrode layer is 200-600 nm, for example, 200 nm, 300 nm, 400 nm, 500 nm or 600 nm.

[0020] Preferably, the thickness of the window layer is 100-200 nm, for example, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm or 200 nm.

[0021] Preferably, the thickness of the light absorbing layer is 2-6 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, or 6 μm.

[0022] Preferably, the thickness of the back electrode layer is 100-900 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or 900 nm.

[0023] In a second aspect, the present invention provides a method for preparing a thin-film solar cell according to the first aspect, the method comprising the following steps:

[0024] A glass substrate is provided.

[0025] A front electrode layer, a window layer, a light absorbing layer and a back electrode layer are sequentially deposited on the glass substrate.

[0026] Laser scribing is performed to form a plurality of grooves by etching the back electrode layer and a portion of the light absorbing layer with a laser.

[0027] Preferably, the laser power of the laser scribing is 1-3 W, for example, 1 W, 1.5 W, 2 W, 2.5 W or 3 W.

[0028] In the present invention, the laser scribing depth range (i.e., the ratio of the scratching depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):1) greatly increases the process window of laser power without affecting the isolation effect of the battery electrodes. It can also effectively prevent the risk of short circuits, thereby improving the photoelectric conversion efficiency of the battery.

[0029] Preferably, the wavelength of the laser used for laser scribing is 1064 nm.

[0030] Preferably, the pulse frequency of the laser scribing is 500-1500 KHz, for example, 500 KHz, 1000 KHz or 1500 KHz.

[0031] In the present invention, the laser scribing depth range (i.e., the ratio of the scratching depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):1) greatly increases the process window of the laser pulse frequency, avoiding excessive energy concentration leading to local overheating. This can prevent excessive melting, deformation or thermal diffusion of the material due to overheating, thereby reducing the mixing or migration of the electrode and the adjacent layer materials caused by thermal effects, reducing the probability of short circuit phenomena, and thus improving the photoelectric conversion efficiency of the battery.

[0032] Preferably, during the laser scribing, the scanning speed of the laser is 1000-3000 mm / s, for example, 1000 mm / s, 1500 mm / s, 2000 mm / s, 2500 mm / s or 3000 mm / s.

[0033] In the present invention, the laser scribing depth range (i.e., the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):1) greatly increases the process window of the laser scanning speed, reduces the formation of residual particles, and reduces the risk of short circuits. It also reduces thermal stress concentration, effectively prevents the occurrence of curling, and avoids short circuits caused by contact between electrodes and other layers due to curling, thereby improving the photoelectric conversion efficiency of the battery.

[0034] Preferably, in the laser scribing, the spot diameter is 15-25 μm, for example, 15 μm, 20 μm or 25 μm.

[0035] In summary, in the present invention, by controlling the laser scribing depth range (i.e., the ratio of the scratching depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):1), and using appropriate laser power and spot diameter, it is possible to ensure that the laser energy is accurately distributed in the scribing area, so that the material is removed as designed. At the same time, a suitable scanning speed can ensure the accuracy of the scribing lines and avoid uneven line thickness or deviations; the effect of the laser energy in the depth direction can be precisely controlled to achieve precise etching of the film layer, ensuring that sufficient material is removed to achieve electrode isolation without excessive etching that causes damage to the underlying structure. Therefore, the systematic coordination of multiple parameters can make the scribing process more stable, help reduce residual particles, reduce curling, and reduce the possibility of short circuits.

[0036] Preferably, the deposition methods of the front electrode layer, window layer, light absorption layer and back electrode layer independently include any one of CVD (chemical vapor deposition) method, PVD (physical vapor deposition) method, CSS deposition (chemical solution spin coating deposition) method, electrodeposition method or thermal evaporation method, or a combination of at least two of them.

[0037] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) By penetrating the back electrode layer and cutting off part of the light absorption layer, the present invention not only reduces the process difficulty, expands the process window, and increases the fault tolerance, but also effectively prevents residual particles from the scribe line from contacting the front electrode layer and causing a local short circuit in the thin-film solar cell. At the same time, the curling of the groove after lamination and packaging does not cause the metal to contact and conduct with the front electrode layer, thus avoiding the problem of local short circuit in the thin-film solar cell. Therefore, this design greatly reduces the impact of the groove scratching on the conversion efficiency of the thin-film solar cell.

[0040] (2) In the present invention, the ratio of the scratch depth of the light absorption layer to the total thickness of the light absorption layer is used to prevent the occurrence of local short circuits and improve the performance and stability of the battery. Secondly, it is beneficial to improve the battery's absorption and utilization efficiency of light, thereby improving the battery's photoelectric conversion efficiency. Moreover, it helps to enhance the stability of the battery structure, especially to have a certain inhibitory effect on problems such as curling and warping that are prone to occur in the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic structural diagram of the thin-film solar cell provided in Example 1 of the present invention.

[0042] Figure 2 This is a schematic structural diagram of the thin-film solar cell provided in Comparative Example 1 of the present invention.

[0043] Among them, 1-glass substrate; 2-front electrode layer; 3-window layer; 4-light absorption layer; 5-back electrode layer. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Example 1

[0046] This embodiment provides a thin film solar cell, the structural diagram of which is shown in FIG. Figure 1 As shown, the thin film solar cell includes a glass substrate 1 , on which a front electrode layer 2 , a window layer 3 , a light absorbing layer 4 and a back electrode layer 5 are sequentially stacked.

[0047] The thin film solar cell has a plurality of grooves, which penetrate the back electrode layer 5 and partially cut through the light absorption layer 4 .

[0048] The ratio of the scratch depth of the light absorbing layer 4 to the total thickness of the light absorbing layer 4 is 0.5:1.

[0049] Among them, the material of the front electrode layer 2 is FTO with a thickness of 400nm; the material of the window layer 3 is CdS with a thickness of 150nm; the material of the light absorption layer 4 is CdTe with a thickness of 4μm; the material of the back electrode layer 5 is Mo with a thickness of 500nm.

[0050] This embodiment also provides a method for preparing the thin-film solar cell, which comprises the following steps:

[0051] (1) Provide a glass substrate.

[0052] (2) Using the PVD method, a FTO layer is sputter-deposited on the glass substrate, and then a window layer is deposited on the FTO layer using the CSS deposition method, and then a light absorption layer is deposited on the window layer using the CSS deposition method, and then a back electrode layer is sputter-deposited on the light absorption layer using the PVD method.

[0053] (3) Using a laser scribing method, a laser with a wavelength of 1064 nm is used to etch the back electrode layer and part of the light absorption layer to form several grooves.

[0054] The laser power of the laser scribing is 2W, the pulse frequency of the laser scribing is 1000KHz, the scanning speed of the laser is 2000mm / s, and the spot diameter is 20μm.

[0055] Example 2

[0056] This embodiment provides a thin-film solar cell, which includes a glass substrate. A front electrode layer, a window layer, a light absorption layer, and a back electrode layer are sequentially stacked on the glass substrate.

[0057] The thin film solar cell has a plurality of grooves, which penetrate the back electrode layer and partially cut through the light absorption layer.

[0058] The ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.45:1.

[0059] Among them, the material of the front electrode layer is FTO with a thickness of 200nm; the material of the window layer is CdSe with a thickness of 100nm; the material of the light absorption layer is CdTe with a thickness of 2μm; the material of the back electrode layer is Al with a thickness of 100nm.

[0060] This embodiment also provides a method for preparing the thin-film solar cell, which comprises the following steps:

[0061] (1) Provide a glass substrate.

[0062] (2) Using the PVD method, a FTO layer is sputter-deposited on the glass substrate, and then a window layer is deposited on the FTO layer using the CSS deposition method, and then a light absorption layer is deposited on the window layer using the CSS deposition method, and then a back electrode layer is sputter-deposited on the light absorption layer using the PVD method.

[0063] (3) Using a laser scribing method, a laser with a wavelength of 1064 nm is used to etch the back electrode layer and part of the light absorption layer to form several grooves.

[0064] The laser power of the laser scribing is 1.9 W, the pulse frequency of the laser scribing is 900 KHz, the scanning speed of the laser is 2000 mm / s, and the spot diameter is 19 μm.

[0065] Example 3

[0066] This embodiment provides a thin-film solar cell, which includes a glass substrate. A front electrode layer, a window layer, a light absorption layer, and a back electrode layer are sequentially stacked on the glass substrate.

[0067] The thin film solar cell has a plurality of grooves, which penetrate the back electrode layer and partially cut through the light absorption layer.

[0068] The ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.55:1.

[0069] Among them, the material of the front electrode layer is FTO with a thickness of 600nm; the material of the window layer is CdSeTe with a thickness of 200nm; the material of the light absorption layer is CdTe with a thickness of 6μm; the material of the back electrode layer is Mo with a thickness of 900nm.

[0070] This embodiment also provides a method for preparing the thin-film solar cell, which comprises the following steps:

[0071] (1) Provide a glass substrate.

[0072] (2) Using the PVD method, a FTO layer is sputter-deposited on the glass substrate, and then a window layer is deposited on the FTO layer using the CSS deposition method, and then a light absorption layer is deposited on the window layer using the CSS deposition method, and then a back electrode layer is sputter-deposited on the light absorption layer using the PVD method.

[0073] (3) Using a laser scribing method, a laser with a wavelength of 1064 nm is used to etch the back electrode layer and part of the light absorption layer to form several grooves.

[0074] The laser power of the laser scribing is 2.1 W, the pulse frequency of the laser scribing is 1100 KHz, the scanning speed of the laser is 2000 mm / s, and the spot diameter is 22 μm.

[0075] Example 4

[0076] The difference between this embodiment and embodiment 1 is that the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.3:1.

[0077] The rest of the preparation methods and parameters remained the same as in Example 1.

[0078] Example 5

[0079] The difference between this embodiment and embodiment 1 is that the ratio of the scratching depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.7:1.

[0080] The rest of the preparation methods and parameters remained the same as in Example 1.

[0081] Example 6

[0082] The difference between this embodiment and embodiment 1 is that the laser power of the laser scribing is 0.5W.

[0083] The rest of the preparation methods and parameters remained the same as in Example 1.

[0084] Example 7

[0085] The difference between this embodiment and embodiment 1 is that the laser power of the laser scribing is 3.5W.

[0086] The rest of the preparation methods and parameters remained the same as in Example 1.

[0087] Example 8

[0088] The difference between this embodiment and embodiment 1 is that the pulse frequency of the laser scribing is 400 KHz.

[0089] The rest of the preparation methods and parameters remained the same as in Example 1.

[0090] Example 9

[0091] The difference between this embodiment and embodiment 1 is that the pulse frequency of the laser scribing is 1600 KHz.

[0092] The rest of the preparation methods and parameters remained the same as in Example 1.

[0093] Example 10

[0094] The difference between this embodiment and embodiment 1 is that during the laser scribing, the scanning speed of the laser is 800 mm / s.

[0095] The rest of the preparation methods and parameters remained the same as in Example 1.

[0096] Example 11

[0097] The difference between this embodiment and embodiment 1 is that during the laser scribing, the scanning speed of the laser is 3200 mm / s.

[0098] The rest of the preparation methods and parameters remained the same as in Example 1.

[0099] Comparative Example 1

[0100] This comparative example provides a thin film solar cell, the structural diagram of which is shown in FIG. Figure 2 As shown, the thin film solar cell includes a glass substrate 1, on which a front electrode layer 2, a window layer 3, a light absorption layer 4 and a back electrode layer 5 are sequentially stacked.

[0101] The thin film solar cell has a plurality of grooves, which penetrate the back electrode layer 5 , the light absorption layer 4 and the window layer 3 .

[0102] Among them, the width of several grooves is 20μm; the material of the front electrode layer 2 is FTO, with a thickness of 500nm; the material of the window layer 3 is CdS, with a thickness of 150nm; the material of the light absorption layer 4 is CdTe, with a thickness of 4.5μm; the material of the back electrode layer 5 is Mo, with a thickness of 500nm.

[0103] This comparative example also provides a method for preparing the above-mentioned thin-film solar cell, which comprises the following steps:

[0104] (1) Provide a glass substrate.

[0105] (2) Using the PVD method, a FTO layer is sputter-deposited on the glass substrate, and then a window layer is deposited on the FTO layer using the CSS deposition method, and then a light absorption layer is deposited on the window layer using the CSS deposition method, and then a back electrode layer is sputter-deposited on the light absorption layer using the PVD method.

[0106] (3) Using laser scribing, a laser with a wavelength of 1064 nm is used to etch through the back electrode layer, the light absorption layer and the window layer to form several grooves.

[0107] Among them, the laser power of laser scribing is 2.5W, the pulse frequency of laser scribing is 1500K, the duty cycle is 0.5, the focal length is -1mm, the laser scanning speed is 1000mm / s, and the spot diameter is 20μm.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.1:1.

[0110] The rest of the preparation methods and parameters remained the same as in Example 1.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 1 is that the ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is 0.9:1.

[0113] The rest of the preparation methods and parameters remained the same as in Example 1.

[0114] Performance Testing

[0115] Photoelectric performance tests were performed on the thin-film solar cells provided in the above embodiments and comparative examples.

[0116] Test article: Thin-film solar cell module (CdTe), 2400x1200x3.2mm

[0117] Test conditions include: AM1.5, 1000W / m2, 25±2℃

[0118] The test results are shown in Table 1.

[0119] Table 1

[0120]

[0121] analyze:

[0122] As shown in Table 1, by penetrating the back electrode layer and partially severing the light absorption layer, the present invention not only reduces process difficulty, expands the process window, and increases fault tolerance, but also effectively prevents residual particles from the scribe line from contacting the front electrode layer and causing local short circuits in the thin-film solar cell. Furthermore, the curling of the groove after lamination and packaging does not cause contact and conduction between the metal and the front electrode layer, thus avoiding the problem of local short circuits in the thin-film solar cell. Therefore, this design greatly reduces the impact of the groove scribe on the conversion efficiency of the thin-film solar cell.

[0123] By comparing Example 1 with Examples 4-5, it can be seen that if the ratio of the scratching depth of the light absorption layer to the total thickness of the light absorption layer is small, it will lead to increased energy loss during current transmission in the battery, reduced short-circuit current, and reduced fill factor, affecting the battery conversion efficiency; if the ratio of the scratching depth of the light absorption layer to the total thickness of the light absorption layer is large, it will cause residual particles to contact the front electrode layer, causing local short circuit of the thin-film solar cell, affecting the battery conversion efficiency.

[0124] By comparing Example 1 with Examples 6-7, it can be seen that different laser powers have different scratching effects when other conditions are the same. If the scratching laser power is too small, the scratching depth is insufficient, and an internal short-circuit channel is easily formed. Poor electrode contact will increase the contact resistance, resulting in increased energy loss during current transmission and a reduced fill factor, which ultimately leads to a decrease in photoelectric conversion efficiency. If the laser power of laser scratching is too large, the material is excessively damaged, thereby forming some unexpected conductive channels inside the battery, causing short-circuit problems. In addition, excessively high laser power will destroy the crystal structure of the thin film material, generate a large number of defects, promote carrier recombination, and ultimately lead to a decrease in the photoelectric conversion efficiency of the battery.

[0125] By comparing Example 1 with Examples 8-9, it can be seen that different laser pulse frequencies have different scratching effects when other conditions are the same. If the pulse frequency of laser scratching is too small, the scratched part of the light absorption layer may appear uneven due to the uneven distribution of laser scratching energy. When the battery is working, this uneven damage may cause confusion in the transmission process of photogenerated carriers, increase the transmission of carriers on unintended paths, and thus lead to the occurrence of short circuits, affecting the battery conversion efficiency; if the pulse frequency of laser scratching is too large, it may cause excessive ablation of the material, resulting in thermal damage to the light absorption layer, causing direct conduction between different functional layers inside the battery, forming a short-circuit channel, causing short-circuit problems, and deteriorating carrier transmission performance, and reducing battery efficiency.

[0126] By comparing Example 1 with Examples 10-11, it can be seen that different laser scanning speeds have different engraving effects when other conditions are the same. If the laser scanning speed is too low during laser engraving, the heat-affected zone will expand, excessive ablation or melting will occur, resulting in a decrease in processing accuracy, increased roughness of the cut surface, and uneven edges, which will affect the battery conversion efficiency; if the laser scanning speed is too high during laser engraving, it will lead to insufficient energy, reduced processing accuracy, incomplete cutting, and affect the battery conversion efficiency.

[0127] By comparing Example 1 with Comparative Example 1, it can be seen that if the groove runs through the back electrode layer, the light absorption layer and the window layer, not only will tiny metal back electrode particles be generated after scribing, but curling will also occur. The curling will cause the metal to be conductive with the FTO after lamination packaging, causing a short circuit in the solar cell and affecting the conversion efficiency.

[0128] From the comparison between Example 1 and Comparative Examples 2-3, it can be seen that if the ratio of the scratching depth of the light absorption layer to the total thickness of the light absorption layer is too small, it will lead to increased energy loss during current transmission in the battery, reduced short-circuit current, and reduced fill factor, affecting the battery conversion efficiency; if the ratio of the scratching depth of the light absorption layer to the total thickness of the light absorption layer is too large, it will cause residual particles to contact the front electrode layer, causing local short circuit of the thin-film solar cell, affecting the battery conversion efficiency.

[0129] It should be noted that while the present invention illustrates the process method through the above-described embodiments, the present invention is not limited to the above-described process steps, and does not necessarily rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A thin film solar cell, characterized in that: The thin film solar cell comprises a glass substrate, on which a front electrode layer, a window layer, a light absorbing layer and a back electrode layer are sequentially stacked; The thin film solar cell has a plurality of grooves, the grooves penetrate the back electrode layer and partially cut through the light absorption layer; The ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.2-0.8):

1.

2. The thin film solar cell according to claim 1, characterized in that: The ratio of the scratch depth of the light absorbing layer to the total thickness of the light absorbing layer is (0.4-0.6):

1.

3. The thin film solar cell according to claim 1 or 2, characterized in that: The material of the front electrode layer includes any one of FTO, ITO or BZO or a combination of at least two thereof; Preferably, the material of the window layer includes any one of CdS, CdSe or CdSeTe or a combination of at least two thereof; Preferably, the material of the light absorbing layer includes CdTe; Preferably, the material of the back electrode layer includes any one of Mo, Cr or Al, or a combination of at least two of them.

4. The thin film solar cell according to any one of claims 1 to 3, characterized in that: The thickness of the front electrode layer is 200-600 nm; Preferably, the thickness of the window layer is 100-200 nm; Preferably, the thickness of the light absorbing layer is 2-6 μm; Preferably, the thickness of the back electrode layer is 100-900 nm.

5. A method for preparing a thin-film solar cell according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: providing a glass substrate; Depositing a front electrode layer, a window layer, a light absorbing layer and a back electrode layer in sequence on the glass substrate; Laser scribing is performed to form a plurality of grooves by etching the back electrode layer and a portion of the light absorbing layer with a laser.

6. The preparation method according to claim 5, characterized in that The laser power of the laser scribing is 1-3W; Preferably, the wavelength of the laser used for laser scribing is 1064 nm.

7. The preparation method according to claim 5 or 6, characterized in that: The pulse frequency of the laser scribing is 500-1500 KHz.

8. The preparation method according to any one of claims 5 to 7, characterized in that During the laser scribing, the scanning speed of the laser is 1000-3000 mm / s.

9. The preparation method according to any one of claims 5 to 8, characterized in that In the laser scribing, the spot diameter is 15-25 μm.

10. The preparation method according to any one of claims 5 to 9, characterized in that: The deposition methods of the front electrode layer, the window layer, the light absorption layer and the back electrode layer independently include any one of CVD, PVD, CSS deposition, electrodeposition or thermal evaporation, or a combination of at least two thereof.

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